Compressor unloader mechanism



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Patented May 6, 1947 COMPRESSOR UNLOADER MECHANISM wade n. Wiseman, Michigan city, Ina., signor to Joy Manufacturing Company, a corporation of Pennsylvania f ,12 Claims. 1 `My invention relates to controlling aDlJ-l'atus for pumps, and more particularly to pressure responsive means for controlling automatically the unloading and loading oi a pump, such as an air compressor, to maintain its discharge pressure within desired limits.

It is desirable in certain pumping systems that means extremely sensitive to variations in pressure be provided for controlling automatically the dischargeof iluid from the systems. By providing means which responds to slight changes in pressures at which iluid is discharged from the pumping system and causing such means. as it respondsto the pressure changes, to produce an amplified force for effecting actuation of control devices such as step unloading means, a very sensitive control of the system is obtained. Preferably, in a compressor control system, I utilize selenium relays. i. e., instruments wherein a beam of light. deilected variably by a member moving in accordance with changes in compressor discharge pressure, is caused to sweep across a plurality oi' selenium cells for producing electrical currents which yactuate means controlling the now of operating iluid relative to suitable compressor unloading means. It is not desired that -the production of electrical currents for such control systems be limited to selenium cells, for it is known that other substances than selenium are aiected as to electrical qualities by the variation of illumination. It is also not desired to limit the invention to the use ot light as the radiant energy employed since thermo couples may be used in place of selenium cells, in which case heat rays take the place of light rays. and these rays may be reflected in the same manner as light HYS. i

It is an object of my invention to provide improved means ior controlling the operation of a pumping mechanism. Another object is to provide an improved control system for pumpunloading means. Still another object is to provide in an improved control system for pump Aiin-- loading mechanism, means responsive to radiant energy for eecting actuation of said unloading mechanism, and means responsive to the pump discharge pressure for transmitting radiant energy to said ilrst mentioned means. Yet another object of my invention ls to provide for a pump unloading mechanism an improved control system comprising selenium cells for supplying` electrical energy to eiiect actuation of said unloading mechanism, and means responsive to the pump discharge pressure lfor directing alight beam .on said selenium cells. .Still another object is to provide an extremely sensitive unloading control system for a pump mechanism. Another object is to provide improved compressor controlling ap- Appiication December 30, 194:3, Seth! No. 516,139

Other objects and advantages of the invention will hereinafter more fully appear.

v In the accompanying drawingsthere are shown for purposes oi illustration a preferred form and a modication thereof which the invention may assume in practice.

In these drawings: Fig. 1 is a diagrammatic view or a compound compressor having the preferred form oi my control means associated therewith, `partis of the control meansbeing shown in section to facilitate illustration.

Fig. 2 is a side elevational view of a portion of the compressor control means shown in Fig. 1.

Fig. 3 is an enlarged vertical sectional view showing one of the unloading devices installed in the ends of the compressor cylinders.

y Fig. 4 is an enlarged view or a portion of the control meansl with parts shown in section, the view being taken on the planes of the line 4-4 of Fig. 1. l

Fig. 5 is a sectional view taken on the line 5-5 of Fig. 4. f r

Fig. 6 is a view taken in the plane of Fig. 1 and showing a modification of the control means.

To illustrate 4the invention there is shown a compound compressor, generally designated i. having the improved control means associated therewith and generally designated 2. It will 'be evident, however, that the control means may be utilized with compressors of various types, or with other mechanisms as well, and that the compressor shown herein is merely illustrative of one or the types oi.' compressors with which the control means is adapted for use.

The compressor comprises a base l having a pair of low pressure cylinders 5, 5' and a pair of high pressure cylinders 6, 6 projecting radially therefrom.V Reciprocable within the low and high pressure cylinders are pistons, not shown, connected through suitable means to a crankshaft i journaled within the base I and driven by any suitable power means, not shown. Air is supplied through connections 8, 8' to the low pressure cylinders .5, 6', where it is compressed and discharged through intercoolers-i. 9 and connections il, IU' to the high pressure cylinders i, 6' where .it is compressed again and whence it is discharged to connections Ii, H leading to a. storage tank,not shown, or to a point of use. The compressor cylinders shown are adapted for the compression of air on each stroke of their respective pistons.=and arranged within cylinder heads I2 at bothends ofthe cylinders are unloading devices, ,generally designated I3. The inlet valve devices il, or at least one at each end of each -vcylinder, has, as shown in Fig. 3, a followerfmember i5 which is received within Va. chamber I6 in lthe cylinder.` `head and paratus which is responsive to radiant energy. so engages anfinlet valvgmechanism proper, genl J ,Y Y Y CROSS lilll'llliilltbl; Umlauten erally designated I1, for holding the latter in place within an opening Il connecting the chamber it in communication with a clearance space Il at the end oi the cylinder bore. Air is conducted to the chamber l through an inlet passage 2li, and inlet valves 2i control the now of air from the chamber I5 to the clearance space Il and the cylinder bore. Attached to the outer end of the member l5, as by screws 23, is a cap 24 having a recessed inner surface which cooperates with a recessed end surface on the member l5 to form a chamber 25. A diaphragm 25 is clamped in the chamber 25 between the cap 24 and the member I5, and attached to the diaphragm is a rod 21 extending through an opening in the member I5 and carrying at its inner end a member having -iingers 25 which are adapted to engage the inlet valves to unseat the latter and eiiect unloading. A suitable outer cover element 50 is secured, as by screws 3 I to the cylinder head above the chamber I5, and a tubular clamping screw 32 is threaded through an opening in the cover element into engagement with the cap 24 for holding the member I5 in clamping engagement with the valve mechanism l1. Threaded on the outer end oi the clamping screw is a guard cap 33 having an opening 54 through which pressure ilud may pass. Formed in the cap 24 in axial alinement with the screw 32 is a passage 35 opening into the chamber 25. When pressure iiuid is supplied through the opening 34, the tubular screw 32 and the passage 35 to the chamber 25, the diaphragm 26 is forced inwardly and moves the fingers 25 into engagement with the inlet valves for unseating the latter. When pressure fluid is vented from the chamber 25, the diaphragm 25 is forced outwardly by a spring 55 for moving the fingers out of engagement with the valves.

Valve devices, generally designated 31, 35, 55 and 40, are provided for controlling the now of pressure iiuid relative to the various unloading devices. Each of these valve devices comprises, as shown in Figs. 4 and 5, a valve casing 4| having a central chamber 42 communicable through valve bushings 43 with end chambers 44 and 45. Arranged in the chambers 44 and 45 are valve members 45 and 45 urged by springs 41 toward seats on the valve bushings for controlling the iiow of pressure fluid between these chambers and the central chamber. The valve mem bers 46 and 46 are provided with guide-ribbed portions 48 projecting through the valve bushings into the central chamber to engage opposite sides of a lever 49 which is pivotally connected at one end to the valve casing and is connected at its other end to a plunger 50 extending into a coil of an electromagnet 5I. Pressure uld is supplied to the chambers 45 from a supply line 53 through branch connections 54. The chambers 44 are connected to atmosphere through vent ports 55. The central chamber oi the valve device 31 is connected by a conduit 55 and branch conduits 51 and 58 to the unloading devices in the head ends of the low pressure cylinder 5 and the high pressure cylinder 5. A conduit 59 connects the central chamber of the valve device 3S to branch conduits 50 and 5l leading to the unloading devices in the head ends of the low lpressure cylinder 5' and the high pressure cylinder 5'. The unloading devices in the crank ends of the low pressure cylinder 5 and the high pressure cylinder 5 are connected by conduits 52 and 53 to a conduit 54 leading to the central chamber of the unloading, device 39. A conduit 55 connects the central chamber of the valve device 40 to branch conduits 55 and 51 leading to the unloading devices in the crank ends of the low pressure cylinder 5 and the high pressure cylinder 5'. It will be seen that on energizing the coils of the electromagnets, the levers 49 are swung upwardly about their pivots and force the valves 45' from their seats so that pressure fluid is supplied from the chambers 45 to the central chambers 42 where it enters the conduits 56, 59, 54, 55 and is conducted to the unloading devices for unloading the compressor cylinders. When the coils of the electromagnets are de-energized, the plungers 50 drop and swing the levers 49 about their pivots to open the valves 45 for venting pressure uid from the unloading devices through the vent ports 55 in the lower chambers 44.

The energizing and de-energizing of the electromagnets are controlled by the improved control means 2. This control means, as illustrated, comprises a reflector 'l0 for deiiecting a light beam 1l so that it is directed against light sensitive devices such as selenium cells 12, 13, 14 and 15. The reflector 10 is movably supported so that the deflected light beam may be caused to sweep across the cells and is shown herein as being fixed in any suitable manner to a plate 11 which is pivotally mounted at 'l5 on a member 18. Formed in the member 19 is a recess 50 cooperating with a recess in a cover plate 5| to provide a diaphragm chamber 52 within which a diaphragm I3 is clamped. Fixed to the diaphragm are circular discs 55 carrying a rod 85 which ilts loosely within an opening in a plug 51 and is adapted to be engaged at its outer end by a pointed projection 58 fixed to the plate 11. Surrounding the rod 55 is a coiled spring 89 acting between the plug l1 and the discs 85 to urge the rod 86 in a direction away from the projection 55, Fluid at compressor discharge pressure is supplied through a conduit 50 to the diaphragm chamber 52 where it acts against the diaphragm and tends to move the latter against the force of the spring 89. A shoulder 5i on the member 15 is engageable by the plate 55 for limiting movement oi the rod 55 by compressor discharge pressure. Acting between the plate 11 and the member 19 at the side of the pivot mounting 15 opposite from the projection is a spring 92 which tends to swing the plate about its pivot and hold the projection 55 firmly against the end of the rod 86.

A source of light is provided within a casing 93 supported in any suitable manner-above the selenium cells, herein an electric light bulb 54, and light from the bulb shines through a lens 95 onto the reflector 10. I'he light may of course be located `at any point from which its beam may be deflected to the cells or, if desired, a suitable mounting may be provided for the light in the place of the reflector 10 so that the light shines directly onto the selenium cells and is moved across the cells as the discharge pressure changes. The beam oi light directed toward the selenium cells must be fanned out or expanded angularly in a plane which intersects each of the cells so that all the cells may be illuminated at the same time when the compressor discharge pressure has reached the maximum desired value and it is necessary to unload the compressor completely.

Connected across the selenium cells 12, 13, 14 and 15 are electrical circuits including electromagnets 96. 91, 98 and 99 which are adapted,

' when energized, to move contactors 'I I1, 1I8, |I0

and |20 into engagement with contacts |2I, |22, |23 and |24. The contacts I2I, |22, |23 and |24 are each connected to the power line La, and the contactors ||1, llt, III and |20 are connected, respectively, by conductors |26, |21, |28 and |20 to one end of the 'coils of the electromagnets for the valve devices 21, 20, 29 and 40. I'he other end o! the coils for the valve devices are connected to the power line L1. It will be understood that two sets of electromagneticallyfcontrolled switches have been used between the selenium cells and the valve devices only because the currents produced by the cells are not strong enough to actuate contactors capable oi' carrying currents for actuating the valve devices. For other types of devices controlling the now of operating huid relative to compressor unloading means, an

amplification of the currents produced by the cells may not be necessary.

The mode of operation of the mechanism described is as follows: Assuming that the compressor discharge pressure is low and that the diaphragm 03 is held by the spring 09 in a p'osi tion such that the light beam deected from the reilector 10 passes above the selenium cell vI2 as viewed in Fig. l, then the coils forthe valve devices l1, 420, 29 and 40 will be de-energized and the plungers I will move the valves 46 into positions venting fluid from the unloading mechanisms Il through the exhaust ports 55, and the compressor will operate fully loaded. As the compressor discharge pressure increases, the diaphragm 83 is forced in a direction to swing the plate 11 about its pivot 18 against the force of the spring 92. The reflector 10 swings with the plate 11 and causes the light beam to move angularly toward the selenium cells. As the light beam strikes the selenium cell 12, an electric current is caused to ilow through the electromagnet $6 for moving the contactor |00 into engagement with the contact |05. Current then j sure and swing the reflector 10 until the light beam strikes the selenium cell 12 as well as the cell 12. Electric currents produced by the cells 12 and '13 will cause electrical circuits to be established for operating the valve devices I1 and 28 to supply operating nuid to the unloading devices in the head ends of the low pressure cylinders I, and the high pressure cylinders 0, 0', thereby eiiecting an unloading oi these ends. 0n further increase in discharge pressure, the reilector is moved to a position so that the light beam is directed upon the cells 12, 1l and 14, Current produced by the cell 14 causes circuits to be established for operating the valve device I9 and supplying uid to the unloading devices in the crank ends of the low and high pressure cylinders 5 and V0. At a maximum discharge pressure, the` reected light beam is moved to a position illuminating the cells 12, 13, 14 and 15. At this time all the valve devices I1, 28, 39 and 40 will be operated to eli'ect an unloading oi the head and crank ends of each o! the compressor cylinders.

In the modification o! the invention shown in Fig. 6, the reflector 10 is attached to a Bourdon -tube |20 to which compressor discharge pressure is supplied through the conduit 00. The Bourdon tube |20 responds to variations in the com- 'pressor discharge pressure to movethe reiiector ating the valve devices 21, I8, 39 and 40 to effect a step control oi the compressor unloading devices in the same manner as described in the preferred form of the invention.

As a result of this invention there is produced an extremely sensitive control system for a pump mechanism. It will be noted that the degree of sensitivity of the system may easily be adjusted by varying the distance between the reflector and the selenium cells or by changing the position of the plug 01 so as to vary the opposition onered by the spring 00 to movements oi the diaphragm Il. Advantages of the system will be clearly ilows from the line L1 of the power line through the conductor II4, the electromagnet ||0, the contactor |00, the contact |05 and the conductor I Ii to the other line L: of the power line. Current llowing through the electromagnet I|0 causes the contactor lI1 to be moved into enapparent to those skilled in the art.

While I have in this application specifically described one form and a modiiication thereof which my invention may assume in practice, it will be understood that this form and modification of the same are shown for purposes of illustration and that the invention may be further modied and embodied in various other forms gagement with the 'contact |2I and current then hows through the power line L1, the coil of the valve device 01, the conductor |26, the contactor II1 and the contact I2| to the power line La.

With the energizing of the coil of the valve device 31, the plunger is raised and swings the arm 49 about its pivot opening the valve 40' and permitting the valve 40 to be seated by the spring 41. Fluid then iiows from the supply conduit 53 through the branch conduit 54 to the chamber 45 where it passes the valve 40 to the central chamwithout .departing from its spirit or the scope the appended claims.

What I claim asnew and desire to secure by Letters Patent is:

41.In a pumping mechanism, in combination, apump, driving means for said pump, iluid actuated unloading means for said pump for effecting unloading'while drive continues, means for controlling the ilow of operating iluid relative to said unloading 'means including an element responsive to radiant energy, means for producing a beam of radiant energy, and means controlled ber 42 and is conducted by the conduit 56 and'Y the branch conduits 51 and 58 tothe unloading devices I3 in the head ends of the low and high pressure cylinders 5 and B for effecting an unloading-o! these cylinder ends. Ii the discharge 'i pressure continues to increase, the diaphragm 63 will be forced inwardly by the discharge presby the discharge pressure of said pump for directing said beam'of radiant energy upon said element when the discharge pressure reaches a predetermined maximum value.

2. In a pumping mechanism, in combination, a pump, ydriving means for said pump, fluid actuated unloading meansor said pump vfor effecting -unloading while drive continues, means `for controlling the flow of opcgatingiiuid relative to said 7 unloading means including an element responsive to radiant energy, means for producing a beam of radiant energy, and means responsive to pump discharge pressures for eiecting a striking of said beam upon said element when a predetermined discharge pressure is reached.

3. In a pumping mechanism, in combination, a pump, driving means for said pump, fluid actuated unloading means for said pump operative to perform its unloading function while pump drive continues, means for controlling the ilow of operating iluid relative to said unloading means including an element responsive to light rays, means for producing rays of light, and means responsive to pump discharge pressure for directing said rays of light on said element when a predetermined maximum discharge pressure is reached.

4. In a pumping mechanism, in combination, a pump, fluid actuated unloading means for said pump, means ior controlling the flow of operating iluid relative to said unloading means including an element responsive to light rays, means for producing rays of light, means for deilecting said rays of light into a plane including said element, and means responsive to pump discharge pressure for actuating said deiiecting means to direct said deflected rays of light upon said element.

5. In a compressor mechanism, in combination, a compressor, driving means for said compressor, iluid actuated unloading means operative to eilect a step unloading of said compressor while drive of the latter is continued, means for controlling the ilow of operating iluld relative to said unloading means including a plurality of elements responsive to radiant energyl means for producing a beam of radiant energy, and means responsive to compressor discharge pressure for directing said beam of radiant energy cumulatively upon said elements as the discharge pressure increases so that one element, or a plurality of elements including said one element, shall he subjected to said beam.

6. In a compressor mechanism, in combination, a compressor, fluid actuated unloading means operative to effect a step unloading of said compressor, means for controlling the flow of operating fluid relative to said unloading means including a plurality of selenium cells, means for producing rays of light, and means responsive to compressor discharge pressure for eiecting an interruption of said light rays by said selenium cells.

7. In a compressor mechanism, in combination, a compressor, duid actuated unloadingl means operative to effect a step unloading of said compressor. means for controlling the iiow of operating fluid relative to said unloading means including a plurality of selenium cells arranged in a common plane, means for producing a beam of light, means for deiiecting said beam of light into the plane including said selenium cells and expanding the beam angularly within said plane to a width including all of said cells, and means responslve to compressor discharge pressure for actuating said deecting means to direct said light beam upon said cells.

8. In a compressor mechanism, in combination, a compressor. fluid actuated unloading means operative to effect a step unloading of said compressor, means for controlling the ow of operating iluid relative to said unloading means including a plurality of selenium cells arranged in a common plane, means for producing a beam oi light,.

means for deecting said beam of light into the plane including said selenium cells and expanding the beam angularly within said plane t 8 Width including all of said cells, and means responsive to compressor discharge presure and operating as the discharge pressure increases to actuate said deectlng means and 'direct the light beam cumulatively upon said cells.

9. In a pump mechanism, in combination, a pump, fluid actuated unloading means operative to eiect a step unloading of said pump, means for controlling the ow of operating iiuid relative in said unloading means including a plurality oi elements responsive to radiant energy and arranged slde by side in a common plane, means for directing a beam of radiant energy in said plane o'f sufllcient width to include all of said elements, and means responsive to pump discharge pressure and operating with increases in pressure to actuate said directing means in a direction to move said beam cumulatively upon said elements.

10. In a pump mechanism, in combination, a

pump, driving means for said pump, unloading means for said pump for reducing the work done by the latter while said driving means continues to drive the same, means for controlling said unloading means ncluding an element responsive to radiant energy, means for producing a beam of radiant energy which is adapted to be intercepted by said element, and means responsive to pump discharge pressure for effecting an interception of said beam by said element when a predetermined discharge pressure is reached.

11. In a pump mechanism, in combination, a pump, driving means for said pump, unloading means operative to effect a step unloading of said pump while drive thereof by said driving means continues, means for controlling said unloading means including a plurality of elements responsive to radiant energy each controlling one step of unloading, means for producing a beam of radiant energy which is adapted to be directed cumulatively upon said elements to eilect step unloading progressively, and means responsive to pump discharge pressure for directing said beam cumulatively upon said elements as predetermined pressure changes take place.

12. In a pump mechanism, a pump, driving means for said pump, means for effecting step unloading of said pump to effect unloading thereof to different degrees while drive thereof by said driving means continues, said means for effecting step unloading having for each step a radiant energy responsive control' element, the control elements for the several steps of unloading `arranged within a predetermined area, a source of radiant energy, and means for subjecting said control elements to energy, from said source successively and cumulatively in a predetermined order as compressor discharge pressure increases and for lnterrupting such subjection in reverse order as compressor discharge pressure decreases.

WADE H. WINEMAN.

REFERENCES CITED The following references are of record in the ille of this patent: .y

UNITED STATES PATENTS Number i NameA V Date 2,167,369 Paullln July 25, 1939 1,833,093 Resner NOV, 24, 1931 2,070,617 Olutt Feb, 16, 1937 2,196,999 Loughridge Apr. 16, 1940 1,924,139 Thomas Q Allg. 29, 1933 2,202,087 ChristieV May 28, 1940 2,147,422 BendZ Feb, 14, 1939 

